As Russia intensifies its war in Ukraine - killing civilians and fueling a major refugee crisis - US President Joe Biden has announced a halt to Russian oil imports.

Critics of Russia have said that sanctioning energy exports could be the best or only way for Moscow to withdraw troops.

A full embargo would be more effective if it included European allies, who also want an end to violence in Ukraine and are concerned about the danger posed by Moscow on the European continent.

However, it is still unclear whether Europe will take part in the embargo, although the UK announced on Tuesday that it will gradually give up Russian oil by the end of 2022.

Unlike the United States, the energy sector in Europe is highly dependent on imports from Russia, which is known as the second largest country in the world that exports crude oil, after Saudi Arabia.

If the US can replace the amount it receives from Moscow, Europe can not do so, at least in the near future.

Moreover, any halt in Russian oil exports could boost oil and gas prices on both continents and put consumers, businesses, financial markets and the world economy in trouble.

What about the US halt on Russian oil?

In the wake of rising US oil prices - a gallon averaging US $ 4.17 - the Biden administration has come under increasing pressure to impose further sanctions on Russia, including a ban on oil imports.

For now, a ban extended even by Europe does not seem feasible.

On Monday, German Chancellor Olaf Scholz made it clear that his country - Europe's largest consumer of Russian energy - has no plans to join the ban.

In response, US Deputy Secretary of State Wendy Sherman has indicated that the US can act alone, or with a small group of allies.

"Not every country has done exactly the same thing.

"But we have all accepted that it is necessary to set heavy costs," Sherman said.

House Speaker Nancy Pelosi has voiced support for the US embargo on Russian oil and cited Biden's move, which leads U.S. allies to release 60 million barrels of oil from strategic reserves, including 30 million barrels from US reserves, in order to stabilize the market.

Can only US sanctions hurt Moscow?

The impact on Russia may be minimal.

The United States imports small amounts of Russian oil and does not buy natural gas from it.

Last year, 8 percent of US imports of oil and its products were shipped from Russia.

Because US imports from Russia are modest, Russia can sell that oil elsewhere, perhaps in China or India.

They will surely have to sell it cheaper, because each time fewer and fewer buyers are accepting Russian oil.

"If Russia is eventually blocked by global markets, countries like Iran and Venezuela could be 'welcomed' as oil sources," said Claudio Galimberti, vice president of analytics at Rystad Energy.

These additional resources are likely to stabilize prices.

A team of Biden administration officials has been in Venezuela over the weekend to discuss energy and other issues.

White House spokeswoman Jen Psaki said officials had discussed a range of issues, including energy security.

"By eliminating some of the demand, we aim to lower the price of Russian oil and make Russia less profitable," said Kevin Book, a director at Clearview Energy Partners, a Washington-based company.

"In theory, this is the way to reduce Russia's profit on every barrel it sells," he said.

Maybe not much, but part yes.

"The most important question is whether there will be more pressure from the other side of the Atlantic."

How can this ban affect prices?

The news that the US may stop importing Russian oil has pushed prices to the highest level, as a gallon sold for an average of $ 4.17.

A month ago, a barrel of oil was sold for nearly $ 90.

Now prices have gone up to $ 130 a barrel as buyers have given up on Russian crude oil.

The Shell Company announced on Tuesday that it will stop buying Russian oil and its natural gas, as well as stop all operations in this country, a day after Ukrainian Foreign Minister Dmytro Kuleba, criticized this energy giant for buying of Russian oil.

Energy analysts have warned that prices could go up to $ 160 or $ 200 a barrel if buyers continue to shy away from Russian crude oil.

This trend could lead to US oil prices at $ 5 a gallon, a scenario Biden and other political figures want to avoid.

Are Russian imports falling?

The U.S. oil industry has said it joins the effort to reduce its dependence on external energy sources and is committed to working with the Biden administration and Congress.

Even without sanctions, some American owners of oil refineries have severed contracts with Russian companies.

Imports of Russian refined oil and its products have fallen.

Preliminary data from the US Department of Energy show that imports of Russian crude oil fell to zero in the last week of February.

The Petroleum Institute has said it has no official position on banning Russian oil imports.

However, he has said he will implement any restrictions introduced.

Can Europe do the same?

A ban on Russian oil and natural gas would place a heavy burden on Europe.

Europe receives about 40 percent of its natural gas from Russia for home heating, electricity, and various industries.

This country also meets a quarter of Europe's oil requirements.

European officials are considering ways to reduce their dependence on Russia, but that will take time.

British Business Secretary Kwasi Kwarteng has said his country will gradually phase out imports of oil and its products, "to give the market and businesses enough time to replace Russian imports", which are about 8 per cent of total British demand.

German Economy Minister Robert Habeck on Tuesday defended Europe's decision to exempt the Russian energy sector from Western sanctions.

"The sanctions were deliberately chosen to have an impact on the Russian economy and the regime of Russian President Vladimir Putin, but they were also deliberately chosen to keep us as an economy, and as a nation, for a long time.

"Reckless behavior can lead in the opposite direction," Habeck said.

Russian Deputy Prime Minister Alexander Novak has said Russia will have "every right" to cut off gas supplies to Europe via the Nord Stream I pipeline, in retaliation for Germany for suspending the Nord Stream II pipeline - a project that does not is still functional.

He added that the Russian authorities have not yet made a decision and that "no one would benefit from such a thing."

This statement has been different from what the Russian authorities have done before, saying that they do not consider stopping Russian gas in Europe.

Oil is replaced more easily than natural gas.

Other countries can increase oil production and send it to Europe.

However, most of the oil needs to be replaced, and this would increase prices even more, as that oil has to be transferred from one country to another.

Replacing natural gas that Russia offers to Europe is an almost impossible mission in the short term.

Most of Russia's natural gas to Europe is transported through pipelines.

To replace it, Europe will need to import liquefied natural gas.

The European continent does not have enough pipelines to carry gas from coastal import plants to the most remote areas of the continent.

In January, two-thirds of U.S. liquefied natural gas exports went to Europe.

Some vessels filled with this liquefied gas were originally launched in Asia, but stopped in Europe after buyers offered a better price, according to energy company S&P Global Platts.

US oil and gas producers may tend to produce more natural gas, even though their export equipment is already operating at full capacity.

The equipment and other effort will require years and billions of dollars extra.

/ AP / REL /